Generally speaking, in North America typically only one lane is paved at a time. However, it is possible to pave widths up to 16 ft. or 20 ft, depending upon whether the initial paving width is 8 ft. or 10 ft, respectively. Thus, a screed can be extended from 8 ft. to 16 ft. or from 10 ft. to 20 ft., for instance, by hydraulically extending an extendable screed wing on each side of a main screed (i.e., left and right extensions) via a carriage configured to extend and retract the screed extensions. Outside of North America, sometimes four lanes at a time are paved. As such, the screed can extend up to 44 ft., for instance. For such length of screed (i.e., paving width), the screed extensions may be bolted together, either rear mounted (i.e., mounted to a rear of the main screed), front mounted (i.e., mounted to a front of the main screed), or fixed directly outward from the main screed. In extended-screed cases such as those described above, multiple auger segments, provided in front of the screed, can extend linearly outward from opposite sides of a generally central deposit site where the paving material is deposited.
Uneven or inconsistent distribution of paving material (e.g., asphalt concrete) in front of the screed, particularly in the context of wide-width paving, can change how the screed “floats” on top of the matte (including screed height and/or angle) and can cause surface matte defects, such as holes, bumps, divots and texture imperfections, including an unsuitable open texture or tight texture. For example, uneven or inconsistent distribution of paving material can be a result of paving material underflow and overflow conditions, that is, too little or too much paving material supplied in front of the screed by the auger(s) or segmented auger sets, respectively. Generally speaking, an underflow condition means not enough paving material is provided and a void in the paving material can be created at the screed, for instance, which means the screed can fall and create a divot in the road surface, and an overflow condition means too much paving material is provided, which can cause the screed to climb and create a bump or high spot on the surface of the road. Thus, overflow or underflow conditions can affect the ability of the screed to produce a surface with a high-quality matte (e.g., a flat, smooth matte).
U.S. Pat. No. 8,979,423 describes a method and apparatus for controlling material feed for asphalt pavers. The material feed system can include a screed, a feeder conveyor and a spreader auger. A sensor can measure a material volume and transmit this information to an Electronic Control Module (ECM). This information may be used as target material volume, which the ECM may use to calculate a corresponding conveyor speed and auger speed. The sensor monitors the material volume as paving commences, and the ECM maintains the initial calibrated target size by adjusting the auger and conveyor rotational speeds.